/*

 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

package sun.jvm.hotspot.runtime;

import sun.jvm.hotspot.oops.*;

/** <P> SignatureIterators iterate over a Java signature (or parts of it).

    (Syntax according to: "The Java Virtual Machine Specification" by

    Tim Lindholm & Frank Yellin; section 4.3 Descriptors; p. 89ff.) </P>

    <P> Example: Iterating over

<PRE>

([Lfoo;D)I

0123456789

</PRE>

    using </P>

<PRE>

iterateParameters() calls: do_array(2, 7); do_double();

iterateReturntype() calls:                              do_int();

iterate()           calls: do_array(2, 7); do_double(); do_int();

is_returnType()        is: false         ; false      ; true

</PRE>

*/

public abstract class SignatureIterator {

  protected Symbol _signature;       // the signature to iterate over

  protected int    _index;           // the current character index (only valid during iteration)

  protected int    _parameter_index; // the current parameter index (0 outside iteration phase)

  protected void expect(char c) {

    if (_signature.getByteAt(_index) != (byte) c) {

      throw new RuntimeException("expecting '" + c + "'");

    }

    _index++;

  }

  protected void skipOptionalSize() {

    byte c = _signature.getByteAt(_index);

    while ('0' <= c && c <= '9') {

      c = _signature.getByteAt(++_index);

    }

  }

  // returns the parameter size in words (0 for void)

  protected int parseType() {

    switch(_signature.getByteAt(_index)) {

    case 'B': doByte  (); _index++; return BasicTypeSize.getTByteSize();

    case 'C': doChar  (); _index++; return BasicTypeSize.getTCharSize();

    case 'D': doDouble(); _index++; return BasicTypeSize.getTDoubleSize();

    case 'F': doFloat (); _index++; return BasicTypeSize.getTFloatSize();

    case 'I': doInt   (); _index++; return BasicTypeSize.getTIntSize();

    case 'J': doLong  (); _index++; return BasicTypeSize.getTLongSize();

    case 'S': doShort (); _index++; return BasicTypeSize.getTShortSize();

    case 'Z': doBool  (); _index++; return BasicTypeSize.getTBooleanSize();

    case 'V':

      {

        if (!isReturnType()) {

          throw new RuntimeException("illegal parameter type V (void)");

        }

        doVoid(); _index++;

        return BasicTypeSize.getTVoidSize();

      }

    case 'L':

      {

        int begin = ++_index;

        while (_signature.getByteAt(_index++) != ';') ;

        doObject(begin, _index);

        return BasicTypeSize.getTObjectSize();

      }

    case '[':

      {

        int begin = ++_index;

        skipOptionalSize();

        while (_signature.getByteAt(_index) == '[') {

          _index++;

          skipOptionalSize();

        }

        if (_signature.getByteAt(_index) == 'L') {

          while (_signature.getByteAt(_index++) != ';') ;

        } else {

          _index++;

        }

        doArray(begin, _index);

        return BasicTypeSize.getTArraySize();

      }

    }

    throw new RuntimeException("Should not reach here: char " + (char)_signature.getByteAt(_index) + " @ " + _index + " in " + _signature.asString());

  }

  protected void checkSignatureEnd() {

    if (_index < _signature.getLength()) {

      System.err.println("too many chars in signature");

      _signature.printValueOn(System.err);

      System.err.println(" @ " + _index);

    }

  }

  public SignatureIterator(Symbol signature) {

    _signature       = signature;

    _parameter_index = 0;

  }

  //

  // Iteration

  //

  // dispatches once for field signatures

  public void dispatchField() {

    // no '(', just one (field) type

    _index = 0;

    _parameter_index = 0;

    parseType();

    checkSignatureEnd();

  }

  // iterates over parameters only

  public void iterateParameters() {

    // Parse parameters

    _index = 0;

    _parameter_index = 0;

    expect('(');

    while (_signature.getByteAt(_index) != ')') {

      _parameter_index += parseType();

    }

    expect(')');

    _parameter_index = 0; // so isReturnType() is false outside iteration

  }

  // iterates over returntype only

  public void iterateReturntype() {

    // Ignore parameters

    _index = 0;

    expect('(');

    while (_signature.getByteAt(_index) != ')') {

      _index++;

    }

    expect(')');

    // Parse return type

    _parameter_index = -1;

    parseType();

    checkSignatureEnd();

    _parameter_index = 0; // so isReturnType() is false outside iteration

  }

  // iterates over whole signature

  public void iterate() {

    // Parse parameters

    _index = 0;

    _parameter_index = 0;

    expect('(');

    while (_signature.getByteAt(_index) != ')') {

      _parameter_index += parseType();

    }

    expect(')');

    // Parse return type

    _parameter_index = -1;

    parseType();

    checkSignatureEnd();

    _parameter_index = 0; // so isReturnType() is false outside iteration

  }

  // Returns the word index of the current parameter; returns a negative value at the return type

  public int  parameterIndex()               { return _parameter_index; }

  public boolean isReturnType()              { return (parameterIndex() < 0); }

  // Basic types

  public abstract void doBool  ();

  public abstract void doChar  ();

  public abstract void doFloat ();

  public abstract void doDouble();

  public abstract void doByte  ();

  public abstract void doShort ();

  public abstract void doInt   ();

  public abstract void doLong  ();

  public abstract void doVoid  ();

  // Object types (begin indexes the first character of the entry, end

  // indexes the first character after the entry)

  public abstract void doObject(int begin, int end);

  public abstract void doArray (int begin, int end);

}